Pretty Great
Of course it is fine quality, fast focusing, and tack sharp. I knew all that before I bought it. What has continually stood out to me about my 135 is how BEAUTIFUL my photos turn out; so very pleasing to the eye. For my needs (and low light photography is one of the things I really enjoy) IS would not be a meaningful addition to this lens.
This lens is a bargain. It is also a specialist. It will not do everything of course, but even when you stretch it outside of its forte the result can still be impressive.
The rare annoyance: Make no mistake this lens is NOT a substitute for a 70-200. You will be kind of frustrated if you are trying to use it in place of the 70-200. If you're one of those people trying to choose between the two and are only going to buy one of them, get the zoom (2.8mk2 of course). But seriously, at half the price/size/weight, when you're using the 135 really well, you may never care that you didn't have your big white zoom.
January 29, 2014

all of the rumors are true...
I had read for years that this was perhaps Canon's sharpest prime. After shooting with it for several months now, I have to agree. The focal length is a little bit of an adjustment when shooting casually on a hike or in the street, especially if you are used to a 50mm or zoom, but once you get comfortable, this lens will hardly leave your camera. With a still subject, such as an arranged portrait, this lens shines. The f/2 is plenty big to work with in 95% of conditions, and the lack of IS is not big deal. I would think the focal length would be a bit funny on a crop sensor, but have not tried it yet. I opted for this in place of a 70-200, and have not thought twice about it since. With this price tag, especially with a rebate, every serious shooter should have one.
January 23, 2014

My fave lens
Portraiture is everything to me and I love working the streets with this lens and my 5D3, My only complaint is that Canon choose to use a plastic filter thread on this lens,Extra care must be given to prevent crossthreading. As for weatherproofing, How many folks shoot portraits in the rain? As for IS, I seriously dont believe that the same image IQ could be maintained by adding extra lens elements that IS would require and then pay extra to boot? I believe this lens will go down in history as a classic based on it"s own merits.
May 6, 2013

Amazing lens!
This is without a doubt the best lens I've ever used. I have owned this lens for around 6 months now, and it's a dream to use. I primarily shoot portraits with it. The bokeh it produces wide open is simply amazing. Even though it's not as wide as a 1.8, 1.4, or 1.2 lens, there is something special and unique about the bokeh it creates. The value of this lens is unparalleled for an L-lens in my opinion. I'm really surprised at how cheap it is compared to other prime, L-lenes. You also get a pretty close focusing distance as well, which is nice. If you want a great portrait L-lens, then this should be at the top of your list. The bang for your buck is terrific.
November 9, 2012